Centrifugal pump



Deco I13, @932 L. F. HOFF CENTRIFUGAL PUMP Filed May 16, 1929 INVENTOR Z/F/EH F. HOFF ATTORNEY Patented Dec. 13, 1932 UNITED STATES PATENT orrlca LEIGH P. HOFF, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOlR. TO THE ALLEN- SHEBMAN-HOFF COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION 01! PENNSYLVANIA OENTBIFU'GAL PUMP Application filed m 16, 1929. Serial No. 363,442.

This invention relates to a pump of the centrifugal impeller type adapted for submerged operation and particularly intended for the purpose of pumping liquid which contains 1n suspension a large amount of solid matter of an abrasive character, such as ashes from a steam power plant, and the like.

Among the purposes of the invention are the provision of a pump arrangement which will be free from clogging at the entrance; in which the pump will be at the bottom of a sump or other receptacle containing the solids and liquid to be pumped; in which the bearings and the drive mechanism will be protected from the abrasive action of the entrained solid matter; in which stufling boxes are not required; and which is highly eflicient because little leakage of pumped liquid can occur.

Other aims andpurposes of the invention will be apparent from the following specification, taken in connection with the accompanying drawing, wherein Fig. 1 is a central vertical cross-section through the pump assembly, certain elements being shown in elevation, and

F i 2 is a corresponding cross section showlng a detail of a bearing construction particularly adapted for use with my invention.

As illustrated in Fig. 1, my pump assembly is mounted upon a sump 9 into which ashes and water may be discharged, as through inlet pipe 10.

In the present preferred embodiment the pump assembly includes an impeller casing 11 and an impeller 12 at the bottom of a vertical shaft 13, the shaft, being connected to a drive motor 14 mounted above the top of the sump 9. A cover plate 15 carrying a suitable standard 16, provides supporting means for the driving motor, while the weight of the lower portion of the assembly is primarily carried by flaring side walls 17 which are in turn bolted to the sides of the sump 10 which also provides a collecting funnel for directing the solid and liquid material to the mouth 18 of the impeller casing 11. In the present pump, suitable aligning bearings 19 and 20 for the shaft are provided near the top and bottom of the latter. The top bearing is carried in a suitable adjustable mounting 19A upon the cover plate 15, and the bottom bearing 20 is carried by a member 21 supported by legs 22 rising from the converging support-ing Walls 17 Referring now particularly to the pump, this comprises a casing 11 surrounding an impeller 12 of the usual type, the inlet 18 to the impeller vanes being on the top side of the casing. The casing 11 is secured in any convenient manner, as by bolts, to a flange 23 extending outwardly from the bottom of the converging side walls 17. The solid and liquid material enters the pump through the top opening 18 and is discharged at one side through a discharge pipe 24. Just above the pump inlet 18 the converging walls 17 carry a series of downwardly directed nozzles 25, which may conveniently consist of openings from a hollow ring 26 cast integrally with but externally to the walls 17 just above the opening 18.

A pipe 27 connected to one side of this hollow ring 26 carries a supply of clear water under pressure to the nozzles 25 for the purpose of keeping the material handled by the pump agitated at the pump entrance 18, thus preventing clogging or undue concentration of solid matter.

Since the liquid to be pumped passes into the impeller casing about the impeller shaft and since there is no shaft opening in the casing which requires any stuffing box, it will be seen that my pump is free from the disadvantages of pumps which require high pressure stufiing boxes. There is no opening for liquid to escape from the impeller casing so the pump is correspondingly increased in efiiciency.

The bearing assembly for the pump shaft,

best seen in its general layout in Fig. 1, comprises the upper and lower bearings 19 and 20, the bearing 20 being intended to be submerged. A water-tight casing, shown as a tube 28 surrounds shaft 13 and extends from member 21 to the cover plate 15 below the mounting 19A of the upper bearin 19. The lower bearing 20 is an a aptation o the ordinary type of propeller shaft rubber bearing which is known for marine use, but w1th certain special features, which will be described below, adapting it particularly to the urposes of my invention. The upper hearing may be of an suitable style for its intended purpose, an is herein shown as a ball-thrust bearing, although I do not restrict. myself thereto. The details of the upper bearing form no part of my invention and will not be further described.

Referring particularlyto Fig. 2, the details of construction of my lower bearing 20 include an external sleeve 30 having an upper outwardly extending flange 31 and a lower inwardly extending flange 32. A marine bearing of the usual type, comprising a bronze cylinder 33 and a rubber liner 34, is

mounted within this sleeve and supported against downward displacement by the lower flange 32. The rubber liner constitutes the actual bearing surface upon which the shaft runs. Its inner surface is provided with rifling grooves, as indicated at 35, to permit leakage of water between the shaft and the liner and to insure a supply of lubricating water between these surfaces, as is the usual practice in such bearings. The casing which surrounds the shaft and which contains the column of clear water in which the shaft runs is in turn bolted to the bearing assembly.

To prevent entrance of water carrying abrasive material to the lower bearing, the tube 28 is supplied with clear water through a. pipe 36 near the top, it being intended that the water level in the tube casing will be maintained at a height somewhat above that of the liquid which is being pumped and which surrounds the casing. Liquid may escape from tube 28 through an overflow pipe 37. Liquid may escape from sump 10 through overflow pipe 38 in case the pump clogs or breaks. Ordinarily the level within the tube will be maintained a proximately constant by the leakage past t e lower bearing, and by adjusting the supply of water to equal this leakage.

The cover plate 15 may be provided on one side with an inspection opening or hand hole 39 carryinga glass bulls-eye to permit the operation of the pump to be seen without removing the hand hole late. Such a bullseye is particularly use 111 for enabling the operator to watch the activity of the agitating nozzles, as indicated by a boiling up of water above the pump, and also for enabling him to adjust the clear water supply to the casing 28. This last ad'ustment is accomplished by turning on t e supply valve in the pipe 36 until water begins to run out of the overflow pipe 37, after which the valve is cut down just sufficiently to stop overflow, thus indicating that the supply of water equals the leakage at the bearing 20.

Inasmuch as my improved pump is at the bottom of its source of supply, and, therefore, self-priming,.it is onl necewary in starting to turn on the agitating water, start the supply of clear water to the bearing column, and switch on the driving motor. The only attention necessary is to see that sufficient water is supplied to the agitating nozzle to prevent clogging and to see that the clear water supply to the bearin column is correctly adjusted and maintaine It will be seen from the foregoing that I have constructed a pump which is selfriming and which may be left submerge continuously if necessary, without exposing any but the more rugged parts to the action of the material being handled, which is adapted to handle a wide variety of materials, such for example, as liquids of different specific gravities, either with or without entrained solid matter; wherein any abrasive material carried by the liquid is prevented from reaching and lnjuring bearings; and wherein the moving parts are few, simple, sturdy, and easily replaced. My improved pump is capa le of operating with a minimum of attention and requires little or no intelligent care or adjustment before, during, or after operation.

It will be understood that I do not limit myself to the embodiment of myvinvention herein shown and described, but what I claim is:

1. A pump assembly which includes an impeller pump adapted to be submerged in the liquid to be pumped, a driving motor above said pump, a shaft connecting said pump and said motor, spaced bearings for said shaft, one of the bearings being submerged during pumping and adapted to permit liquid to flow between the bearing and shaft, a casing surrounding said shaft and extending from said submerged bearing to above the level of liquid to be pumped, and means for maintaining a column of clear liquid in said casin having a level above the level of the liqui to be pumped, said means including a conduit extending from said casing to a source of supply of liquid other than that being pumped and an overflow pipe extending from said casing at a point above the maximum level of the liquid being pumped.

2. An impeller pumping unit adapted to pump fluidorne abrasive solids while surrounded thereby, comprising, in combination, an impeller, an impeller housing, a rotatable impeller shaft extending in one direction from the impeller, driving means at the 'opposite end of said shaft, a bearing for said shaft adapted to permit liquid to How between the bearing and the shaft and surrounded by the material being pumped, a casing extending from said bearing to above the level of material to be pumped and surrounding said shaft, and means to maintain fluid other than that being pumped in the casing at a higher level than that of the liquid to be pumped, converging walls defining an inlet opening into the impeller housing around the shaft, and nozzles about said opening adapted to discharge fluid into the stream of entering material for maintaining the fluidity of the same.

3. A pumping assembly comprising, in

said sump and adapted to hold said shaft in alignment, a vertical casing surrounding said shaft and extending upwardly from said bearing, means for supplying lubricating liquid to said casing, a second bearing surrounding said shaft and disposed above said first named bearing, and an overflow pipe from said casing below said second named hearing but above said sump overflow outlet. In testimony whereof I hereunto aflix my signature this 24th day of April, 1929.

LEIGH P. HOFF.

combination, a sump, an intake opening in a bottom wall of said sump, an impeller pump at the said opening, a plurality of agitating nozzles surrounding said opening, a vertical drive shaft for saidpump, a water-lubricated bearing supported within said sump, and adapted to hold the shaft in alignment, a Vertical casing surrounding said shaft and extending upwardly from said bearing, means for maintaining a column of water within said casing higher than the water level in said sump, a second bearing surrounding said shaft above the water level in said casing, and an overflow pipe from said casing below said second-named bearing but above the water level in said sump.

4. A ump which includes a'rotatable impeller s aft, an impeller housing, an impeller in the housing and on the shaft, 9. liquid retaining casing about the shaft provided adjacent one end with a bearing for the shaft which is adapted to permit liquid to flow out of the casing between the shaft and bearing, said bearing having its outlet end spaced from the pump impeller housing, an inlet pipe adapted to convey liquid to said casing and an overflow pipe from said casing above said bearing.

5. pumping assem 1 comprising in combination a receptacle aving a bottom opening, an impeller pump at said opening having a.- vertlcal drive shaft extending throu h said opening, a liquid retaining casmg a ut the shaft rovided adjacent one end with a bearing or the shaft which is adapted to permit liquid to flow out of the casing between the shaft and bearing, an inlet pipe adapted to convey 1i uid to said casmg, an overflow pipe for sai receptacle and an overflow pipe from said casing above said receptacle overflow pipe.

6. A pumping assembly of the class described mcluding in combination, a sump having an overflow outlet and an intake openmg in its bottom wall, an im ller pum dispcsed at said opening, a p urali?oo agitaxing liquid nozzles disposed a ut said opening, a vertical drive shaft for said pum a water-lubricated bearing supported within 

